Switch



8, 1959 B. w. SEWELL 2,900,467

SWITCH Filed Feb. 25, 1944 FIG. 2.

A! 1: OF @0 T4 770 I INVENTOR BEN W SEWELL F163. BY I 7/ I ATT RNEY United States Patent SWITCH Ben W. Sewell, Tulsa, Okla., assignor tothe United States of America as represented by the Secretary of the Navy Application February 25, 1944, Serial No. 523,879 7 Claims. (Cl. 200-80) This invention relates'to a circuit making and breaking device and more particularly to an unshorting switch for use in rotary projectiles.

One object of this invention is to provide in a projectile a switch operable by a body of mercury which is moved by pressure incident to firing the projectile.

Another object of the invention is to providefor use in a rotary projectile an unshorting switch in which a body of mercury is normally retained in contact with a pair of electrodes by a container having a porous member in its Wall through which the mercury can be expelled gun, thus breaking the circuit across the electrodes.

by centrifugal force when the projectile is fired from a A further object of the invention is to provide a device of the character described which is simple and rugged in construction, and positive in operation.

These and other objects of the invention will be apparent from the following specification and the accompanying drawing, in which Fig. 1 is a vertical sectionalview of one form of the novel unshorting switch;

Fig. 2 is a vertical sectional view of another embodiment of the invention; and

Fig. 3 shows a portion of a projectile in order to illustrate the relationship of the switch thereto and to indicate that the projectile rotates during operation of the switch.

In the device shown in Fig. l, the numeral denotes a thin-walled cylindrical casing which is bent over at its outer end 10a to form a small axial opening 11 and is bent over slightly at its inner end 10b to form a large axial opening 12. In the interior of the casing 10 is an electrode '13 which fills most of the interior of the casing and is hollowed to form a chamber 14 which is of diminishing diameter near its outer end. An axial opening 15 in the outer end of the electrode 13 communicates with the chamber 14, and a porous member 16 is placed in the opening 15 for a purpose which will be explained presently. An impermeable diaphragm 17 of non-porous, frangible material may be located between the outer end of the electrode 13 and the outer end portion 10a of the casing, if desired, although the use of this diaphragm is not essential to operation of the device. The porous member 16 can comprise one or more thicknesses of paper, while the impermeable diaphragm 17 usually consists of Bristol board or other similar material strong enough to withstand mechanical shock, yet weak enough to rupture due to the pressures developed during spinning of the projectile.

Held between the inner ends of electrode 13 and the inner end portion 10b of casing 10 is an insulating collar 18 which carries an electrode 19 extending through the collar into the interior of the hollow portion of electrode 13. The electrode 19 has enlarged portions 20 located at each side of collar 18 to retain the electrode in position in the collar. A body of mercury 21 is contained in the chamber formed by electrode *13, porous Patented Aug. 18, 1959 member 16, and collar 18, so as to complete the circuit between electrodes 13 and 19. i

In the operation of the device shown in Fig. 1, the switch is mounted in a projectile in offset relation to the axis of rotation of the projectile with opening 15 and porous member 16 pointing outwardly away from the axis of rotation. In this position, the electrode 19 will lie substantially on a radius of the projectile, and the endof the electrode 19 which lies in the chamber 14 will point outwardly away from the axis of rotation. The device is connected in an electrical circuit, such asa fume circuit in a projectile, with one connector attached to electrode 19 and another connector attached to electrode 13. Y

When the projectile is fired from a gun, the centrifugal" force incident to rotation of the projectile pushes mer-- cury 21 outwardly away from the axis of rotation of the be ruptured by outward movement of the mercury when the centrifugal force reaches a certain value.

The device shown in Fig. 2 is generally similar to the device shown in Fig. l. A casing 22 serves as an electrode and has its outer end portion bent over at 23. The hollow interior chamber 24 of the casing has a portion 25 of diminished internal diameter formed by an inwardly extending shoulder 26 in the interior of the casing. A porous member 27 is held in and fills the opening 25. An impermeable membrane 28 and membrane retaining washer 29 are held between shoulder 26 and the bent over outer end portion 23 of the casing. These members 27 and 28 are of the same types of materials as members 16 and 17. The inner end of the casing wall has a shoulder 30 and an inwardly bent portion 31 adapted to retain an insulating collar 32. An electrode 33 is axially mounted in collar 32 so as to extend into chamber 24. A cup-shaped member 34 is fitted over the outer end of the casing 22 so as to form a chamber 34a for receiving the mercury as it passes out of the chamber 24.

The operation of the device shown in Fig. 2 is generally the same as the operation of the device shown in Fig. 1. When centrifugal force caused by rotation of the projectile reaches a predetermined value, the mercury passes outwardly through porous member 27 and membrane 28 under the actuation of the centrifugal force and breaks the circuit across electrodes 22 and 33. After passing through the porous member in the membrane, the mercury flows into the chamber 34a which retains the mercury. With this device, each unit may be checked for operation by spinning the mercury from its normal position in chamber 24 through the porous membrane 27 into the chamber formed by cup-shaped member 34. The mercury is then returned through the porous member 27 into chamber 24 by centrifugal force after reversing the position of the switch on the rotating testing machine. In so testing the device, the membrane 28 is not used.

I claim:

1. In a switch for use in a projectile, two electrodes forming part of an electric circuit, a body of mercury adapted to complete a circuit across said electrodes, a chamber for said mercury, and flow-restrictive means mounted in a wall of said chamber in offset relation to the axis of rotation of said projectile for normally retaining said mercury in said chamber and through which said mercury is movable at a predetermined, retarded, rate under pressure incident to firing said projectile, whereby the Said circuit is interrupted by dis lacement of the mercury after the passage of a predetermined time interval. v

2- In n un hor ing switch for use in a projectile; a pair of electrodes forming part of an electric circuit, a body of mercury normally completing a circuit across said clcctrodm, a chamber for said mercury, and porous means mounted in a wall of said chamber in offset relation to the axis of rotation of said projectile for norm lly ret i g id mercury in contact with said-el co e and thro gh w h sai mercury is mova le under pressure inci n to fi ng aid projectile, whereby the circuit is broken by displacement of said mercury.-

3. In an unshorting switch for use in a rotary projec tile, a pair of electrodes, a body of mercury normally completing a circuit across said electrodes, ta container normally retaining said mercury in contact with said electrodes and having an opening locat d in a wall of said container in off-set relation to the axis of rotation of said projectile, and a porous member in said opening normally retaining said mercury in said container and through which said mercury is movable under cen tn'fugal force on firing said projectile from a gun, where.- by the circuit is broken by displacement of said mercury.v

4. An unshorting switch for use in a rotating projec tile, comprising, a hollow electrode open at both ends, a second electrode extending into said hollow electrode in spaced relation thereto, an insulating member carrying said second electrode and adapted to close the inner end of said hollow electrode, a body of mercury in said hollow electrode adapted normally to complete a circuit across said electrodes, and a porous element closing the outer end of said hollow electrode so as normally to retain said mercury in said hollow electrode and through which said mercury is movable under centrifugal force on firing the projectile from a gun, whereby the circuit across said electrodes is broken by displacement of said mercury.

5. In a centrifugal unshorting switch for use in a projectile, the combination of a container forming an electrode, a second insulated electrode mounted in a Wall of said container, a quantity of mercury forming a conductor between said electrodes, and said container having a porous wall portion mounted in off-set relation to the axis of rotation of said projectile through which said mercury passes under the influence of said centrifugal force.

6. In a centrifugal switch for use in a projectile, the combination with a casing forming an electrode, and a second insulated electrode mounted in the casing, of an interior wall forming a chamber containing mercury in contact with the electrodes, and also forming a separate receiving chamber, and said wall having a porous portion between the chambers, said porous portion being mounted in an off-set relation to the axis of said projectile.

7. In a centrifugal Switch, the combination with a casing forming an electrode, and a second insulated elec' trode mounted in the casing, of an interior wall forming a chamber containing mercury in contact with the electrodes, and also forming a separate receiving chamber, a non-porous frangible element forming part of the interior wall and open to the receiving chamber, and said interior wall having a porous portion between the mercu y chamber and said element, said porous portion being mounted in an off-set relation to the axis of said projectile.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,917 Van Degrift Mar. 31, 1931 1,917,581 Gillen July 11, 1933 1,954,019 Moore "Apr. 10, 1934 2,164,991 Ingres July 4, 1939 2,410,663 Kohl Nov. 5, 1945 

